Annual report pursuant to Section 13 and 15(d)

Goodwill and Intangible Assets - Narrative (Details)

v3.20.1
Goodwill and Intangible Assets - Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Amortizing Intangibles:      
Amortization charges $ 4.5 $ 4.5 $ 4.3
Finite-Lived Intangible Assets, Amortization Expense, Year Two 4.5    
Amortization expense, year four 4.5    
Finite-Lived Intangible Assets, Amortization Expense, after Year Five 11.9    
Patents [Member]      
Amortizing Intangibles:      
Amortization charges 1.4 1.4 1.4
Finite-Lived Intangible Assets, Amortization Expense, Year Two 1.4    
Amortization expense, year four 1.4    
Finite-Lived Intangible Assets, Amortization Expense, after Year Five 6.1    
Customer Relationships      
Amortizing Intangibles:      
Amortization charges $ 3.1 $ 3.1 $ 2.9
Useful life 12 years 2 months 12 days 12 years 3 months 12 days  
Finite-Lived Intangible Assets, Amortization Expense, Year Two $ 3.1    
Amortization expense, year four 3.1    
Finite-Lived Intangible Assets, Amortization Expense, after Year Five $ 5.8    
Purchased technology, customer relationships and patents | Weighted Average [Member]      
Amortizing Intangibles:      
Useful life 15 years 9 months 18 days 15 years 9 months 6 days  
Finite-Lived Intangible Asset, Weighted Average Period before Next Renewal or Extension 1 year 6 months 2 years 6 months